What if the Amazon rainforest shrank to the point where it could no longer sustain itself? Or the ocean currents around Europe collapsed, freezing the continent? What if all this happened in just a few decades? Climate change is often perceived to be a disaster in slow motion, but a growing number of scientists worry about climate “tipping points”—thresholds in the climate system that, once crossed, could lead to sudden, catastrophic, irreversible changes. How can scientists predict how close such dramatic changes might be and how much devastation they might cause?

Host: Rachel Dobbs, The Economist’s environment editor. Contributors: Jonathan Nash of Oregon State University; Jack Williams of the University of Wisconsin–Madison; James Veale and Liz Thomas of the British Antarctic Survey.